Vaccinations for adolescents in the U.S. (tetanus, diphtheria, and acellular pertussis - Tdap; meningococcal conjugate vaccine - MCV4; Human Papillomavirus (HPV) vaccines - Gardasil and Cervarex) remain well below the Centers for Disease Control and Prevention (CDC) goals, and especially so for the HPV vaccines. These vaccine deficits are pronounced among minority adolescents, constituting an important health disparity. A recent publication by the President's Cancer Panel has called for renewed effort in messaging to adolescents and their parents that would prompt informed decision-making about the adolescent vaccine series, and improved vaccine uptake. Failure to improve this situation will result in a cohort of young adults, especially minority adults, needlessly at risk for a variey of disease sequalae, both short and long-term in nature. Proposed here is smartphone application-based strategy to provide effective messaging about the importance of adolescent vaccination. An initial module smartphone application - Be Vaccinated - BVac - will be systematically developed in Phase I of the project, employing an Expert Advisory Board, a Medical Practitioner Advisory Board, and an iterative series of Parent and Teen focus groups designed to address concerns about vaccination, accurate information about vaccination, and logistical hurdles to vaccination. Focus groups for parents and teens will aid in content definition, and then in multimedia design and usability. The Expert Advisory Board and the Medical Practitioner Advisory Board will review the outcomes of the iterative focus group cycles, and aid the research group in the specifications of the initial module of BVac. The deliverables of Phase I will be the initial BVac module, with a specifications document describing the remaining modules. In Phase II of the project, the remaining BVac smartphone modules will be produced, along with a Spanish version of the BVac modules. A community-level randomized trial of the BVac modules will be conducted, with vaccine uptake as the endpoint outcome. The commercial potential of the BVac smartphone application, in both English and Spanish, will be strong with potential commercial use by Accountable Care Organizations across the U.S.